NAIADACE.'E. 39 



the leaf serrulate, especially towards the apex. Peduncle twice as long 

 as the spike or more. 



Var. 7, decipiens. 

 Plate MCCCCIX. 



TiAcli. Ic. Fl. Germ, et Helv. Vol. VII. Tab. XXX. Fig. 163. 



P. decipiens, Nolle. Baker and Trimen, in Seemann's Journ. Bot. 1SG7, p. 71. Bah. 



Man. Brit. Bot. ed. vi. p. 364. Fries, Summ. Veg. Scand. p. 68 (67). Koch. 



Spu. Fl. Germ, et Helv. ed. ii. p. 779. Reich. I.e. p. 63. 



Leaves indistinctly stalked, oblong-oval or oblong-obovate, apiculate 

 or shortly cuspidate, entire on the margins or subserrulate only at the 

 apex. Stipules much smaller than in vars. a and 3, and with the wing 

 less prominent. Peduncles not more than twice as long as the sjjike. 



In ponds and slow streams. Rather common, and generally dis- 

 tributed in England, and the southern half of Scotland, but absent 

 from the north of the latter country. Frequent throughout Ireland. 

 Xar. /3, in deep water. Var. y, canal at Bath. 



England, Scotland, Ireland. Perennial. Summer, Autumn. 



The largest of the British pondweeds. Stems often more than a 

 yard long, and the leaves from 3 to 10 inches, by 1 to 2 inches broad, 

 with a thick midrib and lax areolation. The stipules of the upper leaves 

 are frequently 2 or 3 inches long, and have 2 or 3 prominent wings 

 on the. Ijack ; the peduncles are 2 to 6 inches long, thicker than the 

 stem. The fruiting-spike 1^ to 3 inches. Nuts larger than in any of 

 the previous species of the genus, except P. natans. 



The plant figured by Reichenbach as P. lucens, var. coriaceus, of 

 Xolte, I have not seen. Mr. William Wilson found a form in Angle.«ea 

 with floating leaves, the lamina about 2 inches long, and the petiole 

 about an inch ; but thev are not distinctly coriaceous. 



The var. ^ is remarkable for the midrib of the leaf running out beyond 

 the point. The leaves also are usually longer and narrower than in 

 \ ar. a, and the peduncles, which are rarely produced, are much longer, 

 often 5 or (i inches. 



Var. 7 (for fresh specimens of which I am indebted to Mr. C. E. 

 Broome, and for dried ones to Mr. T. B. Flower and Mrs. Hopkins, 

 the latter under the manuscript name of " P. Burtoni") appears to be 

 a weak state, in which the plant has been injured, and has thro-wn out 

 luunLTous fresh branches, 'i'lie leaves are rarely above 3 inches long. 

 The stipules are frequently not more than ^ inch, and -wdth the wings 

 much fainter, although they are present in all the specimens I have 

 examined. The fruit is apparently always abortive. Some stress is 

 laid on the fact of the margin not being denticulate ; but so flir as I 

 can judge there are always a few denticulations towards the apex of 

 tlie leaf. There are certainly such in the specimen of P. decipiens 



